Recently, starvation of limited frequency resources has been a serious problem in the field of wireless communication; hence, it is expected to improve frequency availability. Frequency sharing wireless communication may serve as a technology for improving frequency availability. FIG. 18 is a conceptual illustration showing the overall system constitution including two wireless LANs (Local Area Network) using different frequency channels, which is one example of a combination of wireless communication systems sharing frequency bands.
The illustrated wireless communication system includes wireless LAN base stations 10a, 10b and a receiver device 20a. The wireless LAN base station 10a performs communication using a frequency band of a channel CH1 with a center frequency fa. The wireless LAN base station performs communication using the frequency band of a channel CH5 with a center frequency fb (fa<fb).
The receiver device 20a is located at a position reachable by both of the wireless signals of the wireless LAN base stations 10a, 10b, so that the receiver device 20a may receive signals in which wireless signals having the center frequency fa partially interfere with wireless signals having the center frequency fb.
As another example of the technology sharing frequency bands, it is possible to present a wireless LAN system combined with a Bluetooth system (registered trademark) and a WiMAX system (registered trademark); hence, it may be possible to combine different communication systems which share frequencies.
During communication with the wireless LAN base station 10a, for example, a transmitting frequency band of a preferred signal having the center frequency fa partially overlaps (interferes) with a transmitting frequency band of an interference signal having the center frequency fb output from the wireless LAN base station 10b. In this frequency shared wireless communication, the receiver device 20a needs to improve frequency availability by efficiently performing error correction; hence, it is necessary to precisely detect the occurrence of an interference signal overlapped with the frequency band of a preferred signal.
As a technology for detecting the occurrence of an interference signal, a technology for measuring an interference signal by use of a pattern-known signal such as a training signal and a sounding signal has been developed (see Patent Document 1). Another technology for measuring an interference signal by use of a non-transmission interval of burst transmission or a null signal interval deliberately interposed in a data interval has been developed as well.